GIMP Plugin Registry

FX-Foundry/Color/Separate Luminance...

Creates two new layers: one containing the Luminance, and the other the Chroma information in the form of a Grain Merge. Optionally, it will color-enhance (maximize saturation in) the Chroma layer while still keeping it luminance-neutral.

This allows you to do noise-reduction and sharpening on the two layers separately.

Update (23-Jul-2009):
Noticed that highly-saturated colors exceed the ability of the grain-extract/grain-merge to handle without clipping the color, so I have made the excess color get folded into the luminance layer.  read more »

FX-Foundry/Photo/Enhancement/Maximize Local Contrast...
Like Stretch Contrast, but instead of using the minimum and maximum pixel values from the entire image, uses the minimum and maximum in the vicinity of a pixel to compute its new value. Takes a while to run, but really brings out textures. Result is a Grain Merge layer that adjusts values of the original image.

This filter operates on the visible image, not on a layer or selection.  read more »

This filter generates noise in an image. Available noise types are

• Poisson noise
• Gaussian noise
• Uniform noise
• Laplace noise
• Lorentz noise

It is possible to generate (YCbCr) luminance noise only and to apply a gamma correction.

The wavelet sharpen plugin enhances apparent sharpness of an image by increasing contrast in high frequency space. The amount of unsharpness of the original image can be taken into account by adjusting the sharpening radius. As an option you can choose to sharpen the luminance (YCbCr) channel of the image only.  read more »